Oracle Multitenant is an option with Oracle Database 12c that simplifies consolidation, provisioning, upgrades, and more. It is based on an architecture that allows a multitenant container database (CDB) to hold several pluggable databases (PDBs). You can adopt an existing database as a PDB without having to change the application tier. In this architecture, Oracle RAC provides the local high availability that is required when consolidating various business-critical applications on one system.
When using PDBs with Oracle RAC, the multitenant CDB is based on Oracle RAC. You can make each PDB available on either every instance of the Oracle RAC CDB or a subset of instances. In either case, access to and management of the PDBs are regulated using dynamic database services, which will also be used by applications to connect to the respective PDB, as they would in a single instance Oracle database using Oracle Net Services for connectivity.
If you create an Oracle RAC database as a CDB and plug one or more PDBs into the CDB, then, by default, a PDB is not started automatically on any instance of the Oracle RAC CDB. With the first dynamic database service assigned to the PDB (other than the default database service which has the same name as the database name), the PDB is made available on those instances on which the service runs.
Whether a PDB is available on more than one instance of an Oracle RAC CDB, the CDB is typically managed by the services running on the PDB. You can manually enable PDB access on each instance of an Oracle RAC CDB by starting the PDB manually on that instance.